Variable transmission level luffing device for derricks and jib cranes



APH] 2 2, 1947- R. GOODMAN ET Al. 2,419,209

VARIABLE' TRANSMISSION LEVEL LUFFING DEVICE FOR DERRICKS AND JIB CRANESFiled Aug. ll, 1944 2 S'heecSSheet l lwvEwnms;

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April 22, 1947- R. GOODMAN ET AL 2,419,209

VARIABLE TRANSMISSION LEVEL LUFFING DEVICE FOR DERRICKS AND JIB CRANESFiled Aug. 11, 1944 2 Sheets-Sheet 2v Patented pr. 22, 1947 VARIABLETRANSMISSI DEVICE FOR DER/RIC N LEVEL LUFEING KS AND JIB CRANES RobertGoodman and Henry J. Jacoby,

' New York, N. Y.

Application August 11, 1944, Serial No'. 549,006

(Cl.l 212*-8) 1.3 claims.

This inventionrelate's to cranes and derricks having a swinging boom andhas for its main object to provide means whereby when the boom is lufed,that is raised or lowered, on its pivot, the hook, with the loadthereon, will remain in the same horizontal level.

It is obvious that if no such corrections or adjustments are providedthe load will be moved up or down while only a luling of the boom isneeded, and while the operation is for this movement only.

Such a needless raising or lowering of the load during luliingoperations will cause complications in the mechanism, will rcall forheavier structure, will necessitate the use of heavier machinery, andthe expenditure of substantial amountsof power and energy without anyneed or useful purpose for it.

Many methods, schemes, and constructions have been proposed for a socalled level luiiing of derricks or jib cranes, but none of them werepractical and none of them provided an exact level lullng. All of themnecessitate complicated mechanisms, or entail other drawbacks, while,

even so, none of them could provide a real mathematically correct levellufling without any raising or lowering o'f the load. At best, theycould provide, with all their disadvantages, an approximate levelluiling` only. K The object of this invention is to provide meanswhereby a substantially mathematically exact level lufhng of a derrickor ji-b crane may be practiced with comparatively simple mechanisms.

Another object of our invention is to provide constructions and means,as characterized hereinbefore, which may be installed into aI derrick orcrane without otherwise changing their construction or operation, andwhich, therefore, may be easily installed even into existing old devicesof this type. y Y

Still other objects of our invention will be apparent as thespecification` of the same proceeds.

As has been mentioned, ever since the concept of level luliing forderricks or jib cranes first introduced, its inherent advantages, bothin the savingof powerV and in details of operation, were at onceapparent. But because of the pecularities of its requirements, mostproposed schemes, since developed, at best were only able to developapproximate level lufling, or .became so' complicated in constructionthat they could` be used only for relatively light loads, since thestresses encountered with the heavy loads made the particular mechanismsrequiredV for level luing extreinely bulky or impractical.

Many' such schemes have been advanced -involving compensating hangingpulleys, rotating Jibs at the tip of the boom, folding booms, etc. Oneof the earliest schemes advanced is the twin drum system, one lufling.drum and one hook drum so arranged that while the lufng hoist winds incable to raise the boom, the hook drums will play out cable to keep theload level. This scheme, still basically the simplest scheme everadvanced, did not come into much use precisely because while the theorywas sound, the actual resutls were extremely inaccurate, The inac-Acuracy of this method lies in the fact that the relative amounts ofcable to be wound upon one drum and played out on the other drum to keepthe hook level as the boom goes up or down are constantly changing withthechanging angle of the boom.- Thus, since the diameters of the twodrums were xed, and the gearing between the two drums was constant, theamount of cable run on or on the hook drum for each revolution of theluiling. drum was always the same. Thus the original twin drumk methodattempted to solve, with a constant speed ratio between the twodrums, a;problem,- whose every nature required` a variable speed ratio betweenthe two drums, a ratio, in other words,- which constantly was undergoingchange in the very process of lulng theboom.

The result of this situation was to develop approximate level lufngwithin a given range when the angular change of the boom was kept withinthe compass of a few degrees, but as soon as the boom was required toperform over wide changes of radius for the main hook, that is, greatlychanging distances from the center of rotation of the crane or derrick,causing the angle of the boom with the horizontal to vary as much as 60to 70, it became impossible to even approximate level luliing with thistwin drum method.

For this reason, though essentially still'v the simplest scheme, intheory, this basic method has been discarded for more complicatedmethods of compensating the hook against the change in vertical heightof the boom point to approximate a level hook during the luingoperation.-

The eiTect of our invention to vbe described herein, is t'o use standardhoisting and mechanical devices, in combination with our novel elements,so arranged in an unique and new combination that it is possible toachieve, in the basic twin drum method out-lined above, substantiallyperfect and exact level luling over any range of hook radius and for allor any changes in the angle of the boom with the horizontal;

From the given construction of a crane or derrick, each degree change ofboom angle will require a definite amount cf compensating cable from thehook drum changing for every degree in the change of the boom angle, andchanging with the geometry of the construction of every crane orderrick. Such calculations are readily transformed into requiste ratiosbetween the drums for each absolute angle of the boom Vwith thehorizontal.

To achieve this variable ratio between the two drums in a given crane sothat exact amounts of compensating cable will be run off or on the hookdrum to keep the hook level as the boom is raised. or lowered, we haveinstalled between the two drums a variable transmission of anyappropriate, but otherwise possibly of standard, manufacture. The ratiobetween the speeds of the input and output shafts of this transmissionwill be regulated according to this invention directly by 'the motion ofthe boom itself, or of the lufng mechanism. Our invention of using themotion of the boom itself to regulate the speed ratios of a variabletransmission placed between the lufiing and hook drums, will cause exactprecalculated amounts of compensating cable to be run off or on the hookdrum for each revolution of the luiiing drum at any and every angle ofthe boom.

According to this invention the change in ratio between the drums is acontinual process constantly taking place under load, thus insuringexact level motion of the load on the hook while the boom is beingluifed upwards or down at any angle with the horizontal.

i This above described use of a variable transmission operating as afunction of the angle of the boom with the horizontal can be readilyapplied to any existing crane to transform it to a level luffing craneby using a variable transmission of proper horsepower and by installingour novel connection to the boom or to the lu'lng mechanism to fit therequirements of the geometry of the crane.

' This above described method of level luing is applicable to cranesthat handle heavy as well as light loads, since the only extra mechanismneeded, the variable transmission, is a mechanical element installed inthe crane cab, and does not involve the operation of large structuralmembers, as many other methods do.

In the drawings forming a part of this specification and accompanyingthe same,

Fig. 1 is a diagrammatic side elevation of a crane, showing ourinvention installed therein;

Fig. 2 isa diagrammatic plan of the operating mechanism of said crane ona larger scale;

Fig. 3 is a fragmentary detail of a modification, and

Fig. 4 is a detail showing our novel cam secured on the boom of thecrane.

Referring now to the drawings more in detail, by characters ofreference, the numeral l indicates a whirler crane, in general, having abase structure Il, a rotating platform with the upper structure andmachinery thereon, indicated by the numeral l2, on which is built theusual boom I3. carrying the load block and hook lli.

Asv will be' seen from the diagrammatic plan of Fig. 2- a main drum l5is provided for hoisting the load. A load hoisting cable i6 is securedon the drum and is led over a ileeting sheave Ita and other usualconstructions, the details of which are not shown, as they are wellknown to those versed in this art, the cable then is led to a d hoistingblock Il. It will be seen that when the drum l5 is operated in thedirection of the arrow le, the load will be hoisted, while if it isoperated in the opposite direction, the load will be lowered.

An electric motor i3 provides the power for hoisting the load and alsofor luiing the boom,

when desired, as will be more fully described hereinafter. i l f Themotor shaft is connected, through a reducing gearing generally indicatedby the numeral 23, to the hoist drum l5, and the structure so fardescribed may be used independently of the rest of our device, whendesired, to raise or lower the load, without affecting the position ofthe boom i3, as will be understood.

The motor shaft, however, is extended, as at 2 i, and is connectedthrough a magnetic clutch 22, with a first or input shaft 23 of e,variable transmission device used in our invention, and generallyindicated by the numeral 24.

This variable transmission may be of any standard type well known inthis art, whether hydraulic, mechanical, or electrical, as they are wellknown in this art, and the one indicated in the drawings will have asecond or output shaft 25, a pair of cones 2B on the rst shaft '23, anda second pair of cones 21, on said second or output shaft 25, and a widechain 28 connecting the two double cones in the manner best indicated inFig. 2.

The construction and operation of the variable transmission shown in thedrawings is well known in this art. When it is'desired to increase thespeedratiobetween shafts 23 and 25, cones 25 will be caused to near eachother, while cones 2l will be moved farther apart, and in this Inan-Iner belt or chain 28 will be operated by a large driving radius and willoperate on a smaller radius so that the speed of shaft 25 will be largerthan that of shaft 23. Of course, when it is desired to reduce the speedratio, the reverse setting of the respective cones 26 and 21 will beexecuted.

The adjustment of the pairs of cones, and, ultimately of the speedrelation between th'e input and output shafts may be executed through acontrol lever 29, pivoted as at 3B, the connection to the rest of themechanism and operation of which will be understood and is well known inthis art.

Many such double cone and chain type of variable transmission are on themarket, and the one which is illustrated in our drawings for an exampleonly, and no-t in a limiting sense, is manufactured by the Reeves PulleyCo. of N. Y., Inc., and is shown and described in their catalogue, No.(I1-435 its data given on page 55 and designated by Nos. OOO-5. Werepeat, however, that many other types of variable speed control devicesmay be used, whether mechanical, electrical, or hydraulic, controlled bylevers,'switches, valves, handwheels, etc., their control elements beinginfluenced by the bo-om similarly as described for lever 23 in thepresent illustration.

The output shaft 25 is connected with a shaft 3 l, operating the luilingdrum, as will be described presently, through a flexible coupling 32.

The lufing drum is indicated at 33, and a reducing gear mechanism,generally indicated by the numeral 34, is interposed between the lumngdrum 33 and its driving shaft 3 l The numeral 35 indicates anemergencyhydraulic brake for the main hoist drum drive shaft 2i, and the numeral35. indicates a flexible coupling between said hoist drum drive shaftand the shaft 3l of the motor I9. l

Y The arrangement of Fig. 2 is for a case where a single motor is used,both for hoistingtheload and lufilng the boom, while said motor may beused for operating the hoist drum alone, when desired, as will be seen.The lufng cable 38 is secured on the drum 33 and operates the lufng line39, and it will be seen that upon the operation of drum 33, boom I3 ofthe crane will be raised or lowered on its pivot 40.

AS has `been explained hereinbefore, the purpose of our invention is toprovide means whereby the load block I4 with the load thereon willalways move in a horizontal plane, on any movement, upward or downward,of the boom. For this purpose we provide a novel interconnection betweenthe boom and the variable transmission 24. We secure a specificallydesigned grooved periphery cam 4I on the boom, to rotate or rock withthe same.

In the embodiment shown in our drawings, the pivot pins 42 of the boomare stationary. A small pin 43 vmay be secured into oneof said pivotpins and the cam 4I rotatably arranged thereon. An angular member 44 issecured at one end 45'thereof to the cam, at the other end 46 to theboom; In this manner a rigid permanent connection is established betweenthe boom I3 and the cam 4 i, and, it will be seen that upon an upward ordownward swinging of the boom, the cam Will rotate in a right handed orleft handed direction on its pin 43. v

A control cable 4l is secured at one end 48 to the cam 4I, riding in thegroove thereof, and at the other end 49 the control cable is secured tothe control lever 29, of the variable transmission 24.

It will be obvious that when the boom is moved upwardly, as indicated byarrow 5s, cable 41 will be drawn by the cam 4I in the directionindicated by the arrow 5I, will move the lever 49 horizontally, asindicated by the arrow 52, and influence the variable transmission 2e insuch a manner that the hoist drum I5 will play out a cable exactlysufficient to prevent a raising of the hook I4 with the load thereon,while the boom is moved upwardly, and to keep said hook and load exactlyon the same horizontal level, as it has been in the first position oftheboom before luing the same.

In a reverse manner, when the boom is lowered, as indicated by the arrow53, cable 4l will move in the other direction, arrow 54, the cam 4Iplaying .out a predetermined amount of said cable, and

a spring device, diagranimatically indicated at 55, taking up theslackness so produced in cable 4l,

by swinging the `control lever 29 in the opposite direction, (arrow 55a)In this manner the variable transmission 2-4 will be inuenced inan-opposite direction, to a predetermined and precalculated amount,defined by the design of the cam 4I, and as the luing -drum 33`lowersthe boom, the hoist drum I5 will be idly rotated to take up the cablemade loose by the downward swinging of the boom, and, again, keep theload on the same horizontal level, preventing its lowering with thelowering of the boom.

As has been mentioned thereinbefore, from the constructional details anddimensions of a crane, the amount of the cable to be played out by thehoist drum I5, or to be taken up by it, for every angle of luffng of theboom upwardly or downwardly, which may be greatly different at thevarious positions of the boom, may be figured out, and the contour ofthe cam 4I designed accordingly, by methods and calculations `well knownto engineering experts.

Of course, the data and operation of the variable transmission 24, haveto be considered when designing the cam so that the moving of thecontrol lever :is for said transmissi-on, in one direction or the other,by the cam, should produce such a speed ratio between the input andoutput shafts 23 and 25 of the variable transmission, that, at a certainposition of the boom, a certain amount of lung thereof should produce'such a rotation in one direction or another in the hoist drum I5, as toplay out or take up an exact amount of cable needed to keep the load atthe previous horizontal level, as will be understood by those versed inthis art.

Every crane and every desired path for the load will require a dierentcam 44, and that shown `in the figures is for illustration only. rIhecam maybe designed for a straight horizontal movement of the load, or incase 0f fast luiIing cranes in such a manner that at the start and atthe end of the luing operation the load will be caused to rise to asmall extent, to check the lumng operation, or the cam may be designedfor any predetermined path fcr the load, as will be understood andobvious to experts in crane engineering. It is also to be understoodthat the principle and use of our invention may be employed for othermovements of the b-oom, different from the one herein described, as whenthe boom is not raised or lowered but swings on a vertical'axis.

When it is desired to raise or lower the load, only, the clutch 22 willbe disconnected, so that the mot-or Iii only acts on the hoist drum I 5,and is disconnected from the lufling drum 33.

As has been mentioned, we prefer to employ a magnetic clutch, many ofwhich are well known in this art, but,'of course, any other standardtype of clutch may be used, operating mechanically, hydraulically, orelectrically.

At dii we show a magnetic brake of any standard manufacture for the mainhoist, and at 51 a similar appropriate'standard brake for the lufnghoist shaft 3l It will be seen that in the embodiment illustrated inFig. 2, one single motor IS may drive -either the hoist drum I5, alone,operating on the load, or both, the hoist drum i5 and the lufng drum 33,for the lufling operation.

In Fig. 3 we show a portion of a modication 0f this arrangement wherebytwo motors may be used, one for luiiing and one for hoisting the load.

In Fig. 3 the second motor only is shown with the portion of thearrangement wherein it could be attached to the arrangement shown inFig. 2.

In the modication of Fig. 3, operating with two motors, every part wouldremain identical to the ones shown in Fig. 2, with the only differencethat the magnetic `brake 5l is removed from the end 5@ of the luflingdrum drive shaftY 3|, and a second weaker mo-tor 6G is attached to saidshaft SI, as by a nexible coupling e I.

The magnetic brake 5'? will now conveniently be placed at the outer endof the second motor 6B.

In this modification there will be no need to use the heavy motor I9when only a lufiingoperation is needed. In suoli a case the second motor6@ would be energized and it would drive the luiiing drum 33 and thevariable transmission 24, in' which the role of the two shafts wouldbethe reoutput shaft. Since the motor I9 now receives 7 no power, itsrotor would simply run idly with the rotation of the output shaft 23.The output shaft 23 would then operate the idle hoisting drum l throughthe shaft 2| and gearing 2U, as before, the amount of rotation of saiddrum being defined by the angular movement of the boom I3, through theoperation of the cam 4|, as before.

l The heavy motor i9 ywould be used only for the plays out the cable 38,and, vice versa, the drum I5 will play out the cable l when drum 33windsv in its cable 38.

With given drum diameters, and given gear reductions for their shafts 2land 3i, the relative amounts oi the cables wound on, respectively playedofi, of the two drums, will be a direct function of the variabletransmission 2G.

On the other hand, the ratio of speeds of the two 'shafts in theVariable transmission, byour invention, will depend entirely on the boomangle, or the radius of the hook, therefore, the relative amounts ofcables simultaneously wound on one drum and olf the other, will be adirect function of the radius of the main hook.

When our device is used only to raise or lower the load, without luingthe boom, a main hoist control, indicated diagrammatically at 65, willrelease the brake 5% and apply the power to the motor l5. Suchcontrollers and their connections to such magnetic brakes and electricmotors, are now used and well known in this art, therefore the detailsIof them have not been shown in the drawings.

Clutch 22 also may be of a standard make, and is normally disengaged, asit is well known in this art, and, normally, there is no connectionbetween the main hoist and the luiiing hoist, so that upon operation ofthe controller 65, the crane will only raise or lower the load withoutinfluencing the boom.

When luilng operations are desired, a second, luing, controller de willbe used, the operation of which will release both brakes 5% and 5i, saidbrakes being, again, any standard constructions, said controller alsowill engage the clutch 22, as it is well known, whereby power will bedelivered for the hoisting or lufng of the boom, and the lufngoperation, as described hereinbefore, will take place.

in case the two motor system, or modification of Fig. 3, is used, so asto have the power adapted to the special needs of the luiiing hoistonly, then in a similar manner as described, the brakes 56 and El wouldbe reieased, the clutch 22 caused to engage, and driving. power would bedelivered to the motor 6, by well known means, while no power would beallowed to enter the motor is. Motor Si! would then perform the lufngopera- Ition, rotating both drums in the manner described, and the motorshaft of the motor IS would run idly with a speed transferred to it bythe, now output, shaft its of the transmission .24, as has beenindicated hereinbefore.

At i3' a raised position of the boom is indicated, the changed positionsoi` the .hoisting ele- 8 ments being indicated by I6', Ii", and I4 andthe changes in the lufng elements being diagrammatically indicated 33',all by dotted lines, and it will be seenY that hook H and load L willremain in the same horizontal plane P, as indicated by their dottedpositions H' and L.

Since the position of either shafts in the variable transmission is afunction of the position and amount of the cable on the drum, and this,again, is a function of the position of the boom, the principle of ourinvention, in possibly the simplest manner, may be used in such a .waythat the position of one of the shafts, itself, will influence thevariable transmission in the manner and for the objects describedhereinbefore.

From the foregoing description, taken in connection with the drawingsaccompanying the same, and from the remarks and explanations offered,the advantages and methods of construction and operation of ourinvention will be readily understood by those versed in Ithe art towhich our invention appertains, and while we have described the deviceswhich we now consider to be the best embodiments thereof, we desire tohave it understood that they are shown as merely illustrative and no-tlimiting, and that such changes may be made when desired, as are withinthe spirit of this specification and the scope of the claims hereuntoappended.

What we claim as new and 'want to protect by Letters Patent of theUnited States is:

l. In a crane, or the like, having an upwpardly and downwardly swingableboom on which the load is suspended, a hoisting drum with a hoist cablewhereby to raise or lower the load, and a lufng drum to raise or lowerthe boom, in combination therewith, a changeable driving interconnectionbetween the hoisting drum and the lulng drum, and means controlled bythe boom, adapted to continuously influence said interconnection toalter the ratios of rotations between the ltwo drums to desired amountswhereby upon an upward lufiing operation said hoisting drum always willplay out an amount of hoisting cable calculated to prevent any raisingof the load, and vice versa, upon a downward luiiing, said hoisting drumalways will take up suilicient hoisting cable substantially to prevent alowering of the load. -2. In a crane, or the like, having an upwardlyand downwardly swingable boom on which the load is suspended, a hoistingdrum with a hoist cable whereby to raise or lower the load, and aluiiing drum to raise or lower the boom, ini combination therewith, avariable transmission device between said hoisting drum and luing drum,and means automatically reacting on the upward or downward movements of#the 'boom and adapted to continuously change the transmission device,said transmission device then changing the relation between the speedsof thefluiing and hoisting drums in such a manner that predeterminedamounts of hoisting cable will be played out, ortaken in, as necessary'continuously, and at any position of the Iboom, to prevent the raising,respectively lowering, of the load during any luing operation.

3. In a crane, or the like, having an upwardly and downwardly swingableboom on which the load is suspended, a hoisting drum `with a hoist cablewhereby to raise orlower the load, and `a lui-ling drum to raise 01lower the boom, in combination therewith, a variable transmission device.between said hoisting drum and lufng drum, and means automaticallyreacting on the Yupward Vor downward movements of the boom and adaptedto continuously change the transmission device, said transmission devicethen changing the relation between the speeds o1" the lumng and`hoisting drums in such a manner that predetermined amounts 'of hoistingcable will be `played out, or taken in, as necessary, continuously, andat any position of the boom, said means being adapted to cause the loadto be raised to a small extent at the beginning and ending of any inningoperation but to keep the load in the same horizontal plane during therest of the luiiing operation.

4. In a crane, or the like, having an upwardly and downwardly swingableboom on which the load is suspended, a hoisting drum with a hoist cablewhereby to raise o-r lower the load, and a luing drum to raise or lowerthe boom, in combination therewith, a variable transmission devicebetween said hoisting drum andluing drum, and means automaticallyreacting on the upward or downward movements of the boom and adapted tocontinuously change the transmission device, said transmission devicethen changing the relation between the speeds of the lufling andhoisting drums in such a manner that predetermined amounts of hoistingcable will be played out, or taken in, as necessary, continuously, andat any position of the boom, said means being adapted to cause the loadto describe substantially a pren determined path during the luningoperations.

5. In a crane, or the like, having an upwardly and downwardly swingableboom on which the load is suspended, a hoisting drum with a hoist cablewhereby to fraise or lower the load, and a luffing drum to raise orlower the boom, in cornbination therewith, a variable transmission de`vice between said hoisting drum and lufng drum, and means adapted tocontinuously change the transmission device, the said transmissiondevice then changing reiation between the speeds of the luiiing andhoisting drums in such a manner that predetermined amounts of hoistingcab-le will be played out, or taken in, as necessarycontinuous- 1y, andat any position of the boom, to cause the load to describe respectivepredetermined paths at respective luing operations, said means to changesaid transmission device including a member adapted to inuence thetransmission device,

in one or in the other direction, upon its movevment in one or the otherdirection, and means interposed between said member and the boom of thecrane adapted to move said member with the movements of the boom in apredetermined manner.

6. in a crane, or the like, having an upwardly and downwardly swingableboom on which the load is suspended, a hoisting drum with a hoist cablewhereby to raise or lower the load, and a luiiing drum to raise or lowerthe boom, in combination therewith, a variable transmission devicebetween said hoisting drum and lufling drum, and means adapted tocontinuously change the transmission device, said transmission devicethen changing the relation between the speeds 01"' the luing andhoisting drums in such a manner that predetermined amounts of hoistingcable will be played o-ut, or taken in, as necessary, continuously, andat any position of the boom, to cause the load to describe apredetermined path during respective luiT operations, and said means tochange said transmission device including a pivoted lever inuencing thetransmission device, a spring having the tendency to keep said lever ina normal position, an element influenced by the angularfmovement's ofthe boom, and .a connection between said element and said lever, wherebythe movement of said element upon the lumng of the boom in one directionwill rock .said lever out of its normal position, while an oppositemovement of said element will cause a rocking of said lever towards itsnormal position.

' '7. In a crane, or the like, having an upwardly and downwardlyswingable boom on which the load is suspended, a hoisting drum with ahoist cable whereby to raise or lower the load, and a lufring drum toraise or lower the boom, in combination therewith, a variabletransmission device between said hoisting drum and luing drum, and meansadapted to continuously change the transmission device, saidtransmission device then changing the relation between the speeds of theluing and hoisting drums in such a manner that predetermined amounts ofhoisting cable will be played out, or taken in as necessary,continuously, and at any position of the boom, to cause the load todescribe a predetermined path during a lun-lng operation, said means tochange said transmission including a member on said transmission adaptedto move in one or other directions, and thereby iniiuence saidtransmission to effect high-v er or lower speed ratios, respectivelybetween the hoisting and luing drums, a cam rotatable on the pivotof theboom, a connection between the boom and the cam, whereby the cam willrotate in proportion to the angular movements of .the boom, and aconnection between said cam-and said member on the transmission devicewhereby said member will react on the movements of the cam in apredetermined manner. n In a crane, or the like, having an upwardly anddownwardly swingable boom on which the load is suspended, a hoistingdrum with a hoist cable whereby to raise or lower the load, andV Aalufng drum to raise or lower the boom, in c0111-,A bination therewith, avariable transmission device, between said hoisting drum and lulingdrum', and means automatically reacting on the upward or downwardmovements of the boom and adapted to continuously change thetransmission device, said device then changing the relation between thespeeds of the luiing and hoisting drums in such a manner thatpredetermined amounts of hoisting cable will be played out, or taken in,as necessary, continuously, and at any position of the boom, to causethe load to describe respective predetermined paths at respective luft"-ing operations, an electric motor to drive the hoisting drum shaft,means to disconnect said shaft from the hoisting drum and means then toconnect it to the respective end of said transmission device, for aluing operation, said last two disconnecting and connecting means beingadapted to act in the reverse manner for a hoisting operation.

v9. In a crane, or the like, having an upwardly and downwardly swingableboom on which the load is suspended, a hoisting drum with a hoist cablewhereby to raise or lower the load, and a lumng drum to raise or lowerthe boom, in combination therewith, a variable transmission devicebetween said hoisting drum and luiing drum, and means automaticallyreacting on the upward or downward movements of the boom and adapted tochange the transmission device, said transmission device then changingthe relation between the speeds of the luiing and hoisting drums in sucha manner that predetermined amounts of hoisting cable will be playedout, or taken in, as necessary, continuously, and

atany position of the boom, to cause the load to describe apredeterminedpath during a, luing operation, a rst electric motor normally connectedto said-hoisting drum, and adapted to drive the same, means todisconnect said hoisting drum from said transmission device whenhoisting, a second electric motor normally connected to and adaptedtodrive said luiring drum, and means to connect said transmission to saidhoisting drum, means to de-energize said rst motor, and means toenergize said second motor, when lufng.

10. In a crane or the like, having a boom, a hoisting and a lu'ing drum,a combination, of a shaft operatively connected to the hoisting drum, ashaft similarly connected to the lufng drum, a variable transmissiondevice between said two shafts to determine the ratio between theirspeeds, means adapted to change said variable transmission device andthereby change the ratio of rotation between said two shafts, and meansto continuously influence said transmission changing means in accordancewith the movement of the boom.

11. In a crane or the like, as set forth in claim 10, said means tocontinuously influence the transmission changing means including a camsecured on and rockable with the boom.

12. In a crane or the like, as set forth in claim 10, said means tocontinuously influence the transmission vchanging means including la camrockable with the boom, a lever connected to said ratiot changing means,and a connection between said cam and said lever.

13. In a crane, or the like, having an upwardly and downwardly swingableboom on which the load is suspended, a hoisting drum with a hoist cablewhereby to raise or lower the load, and a luing drum to raise or lowerthe boom, in combination therewith, a variable transmission devicebetween said hoisting drum and lufling drum, and means automaticallyreacting on the up- 12 ward or downward movements of the boom andadapted to continuously change the transmission device, said device thenchanging the relation between the speeds of the luing and hoisting drumsin such a manner that predetermined amounts of hoisting cable will beplayed out, or taken in, as necessary, continuously, and at any positionof the boom, to cause the load to describe respective predeterminedpaths at respective luing operations, a source of power to drive thehoisting drum shaft, means to disconnect said shaft from the hoistingdrum, and means then to connect it to the respective end of saidtransmission device, for a luffing operation, said last twodisconnecting and connecting means being adapted to act in the reversemanner for a hoisting operation.

ROBERT GOODMAN.

HENRY J. JACO-BY.

REFERENCES CITED The following references are of record in the file ofthis patent:

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